Which neurotransmitter is a major regulator of mood and behavior and can be chemically altered using drugs like Prozac or Zoloft? a) nitric oxide
b) substance P
c) norepinephrine
d) serotonin
e) acetylcholine

When ash and dust begin to settle on the ground, they eventually become compacted by

About how many years does it take for one cycle of surface water to become deep water and then surface water again in the oceans? 101001,000

12) several teeth were found in an area of flat land covered with trees and plants. the teeth were examined by a paleontologist, and it was determined that the teeth came from a shark. they found many other shark teeth in this area. however, the people who discovered the teeth were puzzled, because there was no source of water near where the fossils were found. what is the paleontologist's best explanation for why the teeth were found in this area? a) sharks used to live on flat land. b) this area was once covered with salt water. c) this area was once covered with freshwater. d) someone buried the shark teeth deep in the ground.